Less than a year after raising the prices of Forever stamps, the U.S. Postal Service is hiking them up once again. The USPS said Wednesday that it filed notice for a two-cent increase that will bring the price of first-class stamps to 60 cents a piece. The agency previously raised the price from 55 cents to its current 58 cents in August 2021. Under the new plan, the price of an international letter will also rise to $1.40. The change would go into effect July 10. President Joe Biden also signed the $107 billion Postal Service Reform Act of 2022 into law Wednesday afternoon. The law is intende…